Briefly explain IVF and ET. What are the conditions in which these methods are advised?

IVF refers to in vitro fertilisation and ET refers to embryo transfer. Gametes from the male and female are collected hygienically and induced to fuse in the laboratory set up under simulated conditions. The zygote formed is collected and is introduced into the uterus of a host or surrogate mother at the appropriate time (secretory phase). Early embryos (up to 8 cells) are generally transferred to the fallopian tube, whereas embryos with more than 8 cells are transferred to the uterus.